Spiral Matrix

using System;
/* Write a program that reads from the console a positive integer number n (1 ≤ n ≤ 20)
 * and prints a matrix holding the numbers from 1 to n*n in the form of square spiral
 * like in the examples below. Examples:
 * n    matrix
 * 4    1  2  3  4
 *      12 13 14 5
 *      11 16 15 6
 *      10 9  8  7 */

class SpiralMatrix
{
    static void Main()
    {
        Console.WriteLine("Enter the side width of the matrix n (n between 1 and 20):");
        int number = 0;

        do
        {
            if (int.TryParse(Console.ReadLine(), out number) && (number >= 1) && (number <= 20))
            {
                break;
            }
            else
            {
                Console.WriteLine("You have entered an invalid data! Try again!");
            }
        } while (true);

        int maxValue = number * number;
        int[,] matrix = new int[number, number];
        int row = 0;
        int column = 0;
        int counter = 1;
        int side = number;

        Console.Clear();
        Console.WriteLine("n  matrix");
        Console.WriteLine("{0}\t",number);

        while (counter <= maxValue)
        {
            //loop for adding in matrix uper horisontal row
            for (int i = 0; i < side; i++)
            {
                matrix[row, column] = counter;
                counter++;
                column++;
            }

            //setting the position of the nex number
            row++;
            side--; //sets the length of side
            column--;

            //loop for adding in matrix right vertical row
            for (int i = 0; i < side; i++)
            {
                matrix[row, column] = counter;
                counter++;
                row++;
            }

            //setting the position of the nex number
            column--;
            row--;

            //loop for adding in matrix lower horisontal row
            for (int i = 0; i < side; i++)
            {
                    matrix[row, column] = counter;
                    counter++;
                    column--;
            }

            //setting the position of the nex number
            row--;
            column++;
            side--;//sets the length of side

            //loop for adding in matrix left vertical row
            for (int i = 0; i < side; i++)
            {
                    matrix[row, column] = counter;
                    counter++;
                    row--;
            }

            //setting the position of the nex number
            column++;
            row++;
        }

        //printing the matrix
        for (int i = 0; i < number; i++)
        {
            for (int j = 0; j < number; j++)
            {
                Console.Write("{0,4}",matrix[i,j]);
            }

            Console.WriteLine();
        }
    }
}